JP2009097732A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the returning amount of refrigerating machine oil to a proper amount without using an electric means such as a pressure sensor, a solenoid valve and a control circuit. <P>SOLUTION: A pressure control valve 30 for controlling an inlet-side pressure P1 of an oil return pipe 28 roughly constant regardless of a discharge-side pressure Pc of a compressor 10, is disposed at an inlet side of the oil return pipe 28 for returning the refrigerating machine oil separated and extracted by an oil separator 12 to the compressor 10. By controlling the return pipe inlet pressure P1 roughly constant, pressure difference at the front and back of the oil return pipe 28 can be kept roughly constant, and the returning amount of the refrigerating machine oil can be kept roughly constant. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus in which refrigeration oil for lubricating a compressor is mixed in a refrigerant.

  In the conventional refrigeration cycle apparatus, the refrigerant discharged from the compressor and the refrigeration oil are separated by an oil separator, and the separated refrigeration oil is returned to the suction side of the compressor so as to prevent the seizure of the compressor. I have to. When, for example, a capillary tube is used as an oil return pipe for returning the refrigeration oil from the oil separator to the compressor, the refrigerating machine oil return amount is determined by the pressure difference before and after the oil return pipe. When the outside air temperature is high, the pressure difference becomes large, the refrigerating machine oil return amount becomes excessive, and the refrigerating capacity decreases. Further, when the outside air temperature is low, the pressure difference becomes small, the refrigerating machine oil return amount is insufficient, and the reliability of the compressor is lowered.

In view of this, the refrigeration cycle apparatus disclosed in Patent Document 1 uses an electric pressure to generate a differential pressure between a high pressure (discharge side pressure) and a low pressure (suction side pressure) in the compressor (that is, a pressure difference before and after the oil return pipe). It detects with a sensor, and adjusts the amount of throttling of an oil return pipe with a solenoid valve based on the detection result, and controls the amount of return of refrigerating machine oil to an appropriate amount.
JP-A-6-74579

  However, since the refrigeration cycle apparatus disclosed in Patent Document 1 requires a pressure sensor, a solenoid valve, and a control circuit, there is a problem that the entire configuration of the refrigeration cycle apparatus is complicated.

  In view of the above points, an object of the present invention is to make it possible to control the return amount of refrigerating machine oil to an appropriate amount without using electrical means such as a pressure sensor, a solenoid valve, and a control circuit.

  The present invention includes a compressor (10) that sucks and compresses refrigerant, an oil separator (12) that is provided on the discharge side of the compressor (10) and separates and extracts refrigeration oil from circulating refrigerant, and oil separation. An oil return pipe (28) for connecting the compressor (12) and the suction side of the compressor (10) to return the refrigeration oil separated and extracted by the oil separator (12) to the compressor (10); A pressure regulating valve (30, 40, 50) which is provided on the inlet side of the pipe (28) and controls the inlet side pressure of the oil return pipe (28) to be substantially constant regardless of the discharge side pressure of the compressor (10); It is characterized by providing.

  Thus, if the pressure on the inlet side of the oil return pipe (28) is controlled to be substantially constant by the pressure regulating valve (30, 40, 50), the pressure on the outlet side of the oil return pipe (28) is substantially constant. The pressure difference before and after the oil return pipe (28) is also substantially constant, and the refrigerating machine oil return amount is also substantially constant. Therefore, the return amount of the refrigerating machine oil can be controlled to an appropriate amount with a simple configuration without using electric means.

  In this case, when the discharge side pressure of the compressor (10) is equal to or higher than the first set pressure, a valve body (301) that closes a passage from the oil separator (12) to the oil return pipe (28), and a valve body ( 301), a pressure regulating valve (30) provided with an orifice (302) that always communicates the upstream side and the downstream side can be used.

  In this way, when the discharge side pressure of the compressor (10) is equal to or higher than the first set pressure, the pressure is transmitted to the downstream side of the valve body (301) via the orifice (302). The pressure on the downstream side of the valve body (301) (that is, the inlet side pressure of the oil return pipe 28) can be controlled to be lower than the discharge side pressure of 10), and an excessive amount of refrigerating machine oil return can be avoided.

  Further, the pressure regulating valves (40, 50) include valve bodies (401, 501) for opening and closing a passage extending from the oil separator (12) to the oil return pipe (28), and the inlet side of the oil return pipe (28). When the pressure is equal to or higher than the second set pressure, the valve body (401, 501) is closed, and when the pressure on the inlet side of the oil return pipe (28) is lower than the second set pressure, the valve body (401, 501) is closed. The valve can be opened.

  In this way, since the inlet side pressure of the oil return pipe (28) can be controlled to be constant, the return amount of the refrigerating machine oil can be controlled to an appropriate amount.

  In addition, the code | symbol in the bracket | parenthesis of each means described in a claim and this column shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a diagram showing a configuration of a refrigeration cycle apparatus according to the first embodiment, and FIG. 2 is a diagram showing a configuration of a main part of the apparatus of FIG.

  The refrigeration cycle apparatus of this embodiment is used to cool the inside of a freezer mounted on a vehicle.

  As shown in FIG. 1, the refrigeration cycle apparatus 1 includes a compressor 10, an oil separator 12, a condenser 14, a liquid receiver 16, an expansion valve 18, an evaporator 20, and a gas-liquid separator 22 as main components. It is said. These components are connected by refrigerant piping.

  The compressor 10 is driven by a traveling engine (not shown) via an electromagnetic clutch, and sucks, compresses, and discharges the refrigerant. The oil separator 12 is provided on the discharge side of the compressor 10, and separates and extracts the refrigeration oil from the refrigerant discharged from the compressor 10. The condenser 14 cools and condenses the high-temperature and high-pressure gas-phase refrigerant that has flowed out of the oil separator 12 with outside air.

  The liquid receiver 16 separates the refrigerant that has flowed out of the condenser 14 into a liquid-phase refrigerant and a gas-phase refrigerant, causes the liquid-phase refrigerant to flow out, and stores excess refrigerant in the cycle. The expansion valve 18 depressurizes the high-pressure refrigerant that has flowed out of the liquid receiver 16. The evaporator 20 evaporates the refrigerant flowing out from the expansion valve 18 and cools the air in the freezer. The gas-liquid separator 22 separates the refrigerant flowing out of the evaporator 20 into a liquid phase refrigerant and a gas phase refrigerant, and returns the gas phase refrigerant to the suction side of the compressor 20.

  The outlet side of the oil separator 12 (ie, between the oil separator 12 and the condenser 14) and the inlet side of the evaporator 20 (ie, between the expansion valve 18 and the evaporator 20) are connected to the hot gas passage. 24 is connected. Through this hot gas passage 24, the high-temperature and high-pressure refrigerant discharged from the compressor 10 is led to the evaporator 20, bypassing the condenser 14, the liquid receiver 16, and the expansion valve 18. The hot gas passage 24 is provided with a bypass valve 26 that opens and closes the hot gas passage 24 and depressurizes the refrigerant flowing through the hot gas passage 24. The bypass valve 26 opens the hot gas passage 24 so that a high-temperature refrigerant flows through the evaporator 20 so that the evaporator 20 is defrosted.

  As shown in FIG. 2, an oil storage chamber 120 for storing refrigeration oil separated from the refrigerant is formed on the lower side of the oil separator 12. The oil storage chamber 120 and the suction side of the compressor 10 (that is, between the compressor 10 and the gas-liquid separator 22) are connected by an oil return pipe 28. The oil return pipe 28 returns the refrigeration oil separated by the oil separator 12 to the suction side of the compressor 10. Specifically, the oil return pipe 28 uses a capillary tube having a predetermined pressure loss.

  In the oil separator 12, a pressure adjusting valve 30 that controls an inlet side pressure (hereinafter referred to as a return pipe inlet pressure) P <b> 1 of the oil return pipe 28 is provided. The pressure regulating valve 30 includes a valve seat 300 provided in an oil return passage connected from the oil separator 12 to the oil return pipe 28, a valve body 301 that contacts and separates from the valve seat 300, and opens and closes the oil return passage. And an orifice 302 that constantly communicates the upstream side and the downstream side of the valve body 301, and a spring 303 that biases the valve body 301 in the valve opening direction. The valve body 300 is biased in the valve closing direction by the discharge side pressure (hereinafter referred to as compressor discharge pressure) Pc of the compressor 10 and is biased in the valve opening direction by the return pipe inlet pressure P1.

  Next, the operation of the refrigeration cycle apparatus 1 of the present embodiment will be described. FIG. 3 shows control characteristics such as the return pipe inlet pressure P1 by the pressure regulating valve 30. As shown in FIG. 3, the compressor discharge pressure Pc increases as the outside air temperature increases, and the outlet side pressure of the oil return pipe 28 (that is, the suction side pressure of the compressor 10; hereinafter referred to as the return pipe outlet pressure). ) P2 is substantially constant.

  First, when the outside air temperature is lower than the set temperature t1 shown in FIG. 3, the valve discharge state of the valve body 301 is maintained by the spring 303 because the compressor discharge pressure Pc is low, and the compressor discharge pressure Pc and the return pipe inlet pressure are maintained. P1 has the same pressure. The compressor discharge pressure Pc when the outside air temperature is the set temperature t1 corresponds to the first set pressure of the present invention.

  When the outside air temperature rises and reaches the set temperature t1, the compressor discharge pressure Pc rises and the force that biases the valve body 301 in the valve closing direction increases. The force that urges the valve body 301 in the valve closing direction by the compressor discharge pressure Pc is larger than the force that urges the valve body 301 in the valve opening direction by the spring 303 and the return pipe inlet pressure P1. The body 301 comes into contact with the valve seat 300 to be in a closed state.

  Therefore, in the region where the outside air temperature is equal to or higher than the set temperature t1, the upstream side and the downstream side of the valve body 301 communicate with each other only through the orifice 302, and the compressor discharge pressure Pc passes through the orifice 302 only through the oil return pipe. Therefore, the return pipe inlet pressure P1 is controlled to be lower than the compressor discharge pressure Pc. By appropriately setting the specification of the orifice 302, the return pipe inlet pressure P1 can be controlled to be substantially constant regardless of the compressor discharge pressure Pc in the region where the outside air temperature is equal to or higher than the set temperature t1.

  Thus, if the return pipe inlet pressure P1 is controlled to be substantially constant by the pressure regulating valve 30, the pressure difference before and after the oil return pipe 28 (ie, P1-P2) becomes substantially constant, and the return amount of the refrigeration oil is also increased. It becomes almost constant. Therefore, the return amount of the refrigerating machine oil can be controlled to an appropriate amount with a simple configuration without using electric means.

  It should be noted that the refrigerating machine oil is always stored in the oil storage chamber 120 of the oil separator 12 so that a necessary amount of the refrigerating machine oil is returned to the compressor 10 when the pressure difference across the oil return pipe 28 becomes the smallest. Thus, the specifications of the return pipe inlet pressure P1 and the oil return pipe 28 are set.

(Second embodiment)
A second embodiment of the present invention will be described. FIG. 4 is a diagram illustrating a configuration of a main part of the refrigeration cycle apparatus according to the second embodiment. This embodiment is different from the first embodiment in the configuration and installation position of the pressure regulating valve. In addition, the same code | symbol is attached | subjected to the same or equivalent part as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 4, in this embodiment, the pressure adjustment valve 40 is installed outside the oil separator 12. Specifically, the pressure regulating valve 40 is disposed between the oil storage chamber 120 of the oil separator 12 and the oil return pipe 28.

  The pressure regulating valve 40 includes a valve seat 400 provided in an oil return passage that extends from the oil separator 12 to the oil return pipe 28, a valve body 401 that contacts and separates from the valve seat 400, and opens and closes the oil return passage. And a diaphragm 403 for driving the valve body 401.

  The two chambers 404 and 405 are partitioned by the diaphragm 403, the first chamber 404 is maintained at a constant pressure, and the return pipe inlet pressure P1 is introduced into the second chamber 405 through the communication hole 406. The valve body 400 is urged in the valve opening direction by the pressure in the first chamber 404, and is urged in the valve closing direction by the return pipe inlet pressure P <b> 1 in the second chamber 405. The set load of the spring 402 can be adjusted by an adjusting screw 407.

  In the pressure regulating valve 40 of the present embodiment, the force that biases the valve body 401 in the valve opening direction by the pressure of the first chamber 404 and the force that biases the valve body 401 in the valve closing direction by the spring 403 are constant. Therefore, the operation of the pressure regulating valve 40 is determined by the return pipe inlet pressure P1 of the second chamber 405.

  Specifically, when the return pipe inlet pressure P1 decreases, the valve closing biasing force that biases the valve body 401 in the valve closing direction by the spring 403 and the return pipe inlet pressure P1 of the second chamber 405 is changed to the first chamber 404. When the pressure becomes smaller than the valve opening urging force that urges the valve body 401 in the valve opening direction, the valve body 401 moves away from the valve seat 400 and the oil return passage is expanded, thereby the return pipe inlet pressure P1. Rises. Further, when the return pipe inlet pressure P1 increases, the valve closing biasing force increases, and when the valve closing biasing force becomes larger than the valve opening biasing force, the valve body 401 moves toward the valve seat 400 and moves to the oil return passage. As a result, the return pipe inlet pressure P1 decreases. In this way, the return pipe inlet pressure P1 is controlled to a constant pressure. This constant pressure corresponds to the second set pressure of the present invention.

  In this way, if the return pipe inlet pressure P1 is controlled to be constant by the pressure regulating valve 40, the pressure difference before and after the oil return pipe 28 becomes substantially constant. Therefore, the return amount of the refrigerating machine oil can be controlled to an appropriate amount with a simple configuration without using electric means.

(Third embodiment)
A third embodiment of the present invention will be described. FIG. 5 is a diagram illustrating a configuration of a main part of the refrigeration cycle apparatus according to the third embodiment. This embodiment is different from the first embodiment in the configuration and installation position of the pressure regulating valve. In addition, the same code | symbol is attached | subjected to the same or equivalent part as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 5, in this embodiment, the pressure adjustment valve 50 is installed outside the oil separator 12. Specifically, the pressure regulating valve 50 is disposed between the oil storage chamber 120 of the oil separator 12 and the oil return pipe 28.

  The pressure regulating valve 50 includes a valve seat 500 provided in an oil return passage that extends from the oil separator 12 to the oil return pipe 28, a valve body 501 that opens and closes the oil return passage by contacting and separating from the valve seat 500, and the valve body 501. Are provided with a spring 502 for biasing the valve 502 in the valve opening direction, a bellows 503 for housing the spring 502 therein, an adjustment screw 504 for adjusting a set load of the spring 502, and a cap 505.

  Further, the opening area of the valve seat 500 (that is, the pressure receiving area of the valve body 501) and the pressure receiving area of the bellows 503 are equal. Accordingly, the compressor discharge pressure Pc acts on the valve body 501 to urge the valve body 501 in the valve opening direction, and the compressor discharge pressure Pc acts on the bellows 503 to apply the valve body 501 in the valve closing direction. The force that strikes is offset.

  Since the force that biases the valve body 501 in the valve opening direction by the spring 503 is constant, the operation of the pressure regulating valve 50 is determined by the return pipe inlet pressure P1 acting on the valve body 501.

  Specifically, when the return pipe inlet pressure P1 decreases, the valve closing force for biasing the valve body 501 in the valve closing direction by the return pipe inlet pressure P1 biases the valve body 501 in the valve opening direction by the spring 503. When it becomes smaller than the valve opening urging force, the valve body 501 moves away from the valve seat 500 and the oil return passage is expanded, thereby increasing the return pipe inlet pressure P1. When the return pipe inlet pressure P1 increases, the valve closing urging force increases. When the valve closing urging force becomes larger than the valve opening urging force, the valve body 501 moves toward the valve seat 500 and moves to the oil return passage. As a result, the return pipe inlet pressure P1 decreases. In this way, the return pipe inlet pressure P1 is controlled to a constant pressure. This constant pressure corresponds to the second set pressure of the present invention.

  In this way, if the return pipe inlet pressure P1 is controlled to be constant by the pressure adjusting valve 50, the pressure difference before and after the oil return pipe 28 becomes substantially constant. Therefore, the return amount of the refrigerating machine oil can be controlled to an appropriate amount with a simple configuration without using electric means.

(Other embodiments)
In each of the above embodiments, the oil return pipe 28 is a capillary tube, but may be a pipe having a fixed throttle.

It is a figure which shows the structure of the refrigerating-cycle apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the principal part of the apparatus of FIG. It is a characteristic view which shows control characteristics, such as the return pipe inlet pressure P1, by the pressure regulation valve 30 of FIG. It is a figure which shows the structure of the principal part of the refrigerating-cycle apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the principal part of the refrigerating-cycle apparatus which concerns on 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Compressor, 12 ... Oil separator, 28 ... Oil return pipe, 30, 40, 50 ... Pressure control valve.

Claims (3)

A compressor (10) for sucking and compressing refrigerant;
An oil separator (12) provided on the discharge side of the compressor (10) for separating and extracting the refrigeration oil from the circulating refrigerant;
An oil return pipe that connects the oil separator (12) and the suction side of the compressor (10) and returns the refrigeration oil separated and extracted by the oil separator (12) to the compressor (10). 28)
A pressure regulating valve (30, provided on the inlet side of the oil return pipe (28), which controls the inlet side pressure of the oil return pipe (28) substantially constant irrespective of the discharge side pressure of the compressor (10). 40, 50). The pressure regulating valve (30) is a valve that closes a passage from the oil separator (12) to the oil return pipe (28) when the discharge side pressure of the compressor (10) is equal to or higher than a first set pressure. The refrigeration cycle apparatus according to claim 1, further comprising a body (301) and an orifice (302) that allows the upstream side and the downstream side of the valve body (301) to always communicate with each other. The pressure regulating valve (40, 50) includes a valve body (401, 501) that opens and closes a passage from the oil separator (12) to the oil return pipe (28), and the oil return pipe (28) When the inlet side pressure is equal to or higher than the second set pressure, the valve body (401, 501) is closed, and when the inlet side pressure of the oil return pipe (28) is lower than the second set pressure, the valve body ( 401, 501) is opened, The refrigeration cycle apparatus of Claim 1 characterized by the above-mentioned.

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